Hello Michael,
These options only controls the range of angles used to initialise the search. If you want to specifically restrict the registration, you may want to look at modifying one of the schedule files.
http://fsl.fmrib.ox.ac.uk/fsl/fslwiki/FLIRT/FAQ#What_are_FLIRT_schedule_files.3F
has some information on doing this.
Kind Regards
Matthew
> Dear FSL users
>
> I would like to use flirt to register images, but constrain the registration such that rotations are permitted only about the z-axis (due to thick slices), or disable angular optimisation altogether in the extreme case (pure translational registration - just to centre the image on a sensible coord system).
>
> I was of the impression the former could be accomplished using the command:
>
> flirt -in MyInputImage -ref MyRefImage -out MyOutImage -omat REG.txt \
> -bins 256 -cost corratio -searchrx -0 0 -searchry -0 0 -searchrz -90 90 -dof 6
>
> However, rotations are about all 3 axes.
>
> Further, I have attempted to disable angular optimisation altogether using:
>
> flirt -in MyInputImage -ref MyRefImage -out MyOutImage -omat REG.txt \
> -bins 256 -cost corratio -nosearch -dof 6
>
> But again there are rotations about all axes.
>
> Could these be bugs? Or is this a syntactic error? Any feedback would be appreciated. I am running fsl 5.0.9 under Ubuntu 14.04.3
>
> Yours
>
> Michael Knight, PhD
> Elizabeth Blackwell Institute early career fellow
> University of Bristol
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